Fungal pathogen-responsive Th17 cells in gut-mouth axis enhance protection against oropharyngeal candidiasis.

Oropharyngeal candidiasis (OPC) is an opportunistic infection caused by Candida albicans. IL-17-mediated immunity driven by Th17 cells plays a crucial role in defense against this infection. However, the location and mechanism by which the Th17 immune response is induced during OPC remain unclear. Here, we show that C. albicans in the gut enhances protection against OPC. Intestinal C. albicans is taken up by the mucosal immune system and triggers a systemic C. albicans-responsive Th17 cell response. Upon oral infection with C. albicans, these Th17 cells migrate from the gut to the oral region and accumulate in the tongue tissue, resulting in antifungal immune responses. The pathobiont-reactive Th17 cells developed in the gut strongly provide IL-17A not only locally in the mouth but also systemically in the serum upon OPC. Our findings highlight that fungal pathogen-responsive Th17 cells in the gut-mouth axis enhance protection against OPC.